http://hdl.handle.net/10033/6885 Sat, 18 May 2013 17:50:01 GMT 2013-05-18T17:50:01Z http://hdl.handle.net/10033/14630 Title: Identification of new acceptor specificities of glycosyltransferase R with the aid of substrate microarrays. Authors: Seibel, Jürgen; Hellmuth, Hendrik; Hofer, Bernd; Kicinska, Anna-Maria; Schmalbruch, Bodo Abstract: Finding opportunities to construct sugar motifs and to transfer them to targets of biological relevance and rapid identification of glycosylation events are important goals for glycobiology and a field of increasing interest. Here we have applied an enzyme microarray screening system for the identification of new acceptor specificities of the glycosyltransferase R (GTFR) from Streptococcus oralis (E.C. 2.4.1.5), which was able to effect the synthesis of sugar motifs in short times and with low amounts of substrate. These observations resulted in the development of a convenient alpha-glycosylation by the non-Leloir glycosyltransferase GTFR, with sucrose as substrate and with different alcohols and amino acid derivatives as acceptors, for the synthesis of glycoethers and glycosylated amino acids not observed with the use of familiar GTFs with high sequence homology. Wed, 01 Feb 2006 00:00:00 GMT http://hdl.handle.net/10033/14630 2006-02-01T00:00:00Z http://hdl.handle.net/10033/12307 Title: 7-O-malonyl macrolactin A, a new macrolactin antibiotic from Bacillus subtilis active against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and a small-colony variant of Burkholderia cepacia. Authors: Romero-Tabarez, Magally; Jansen, Rolf; Sylla, Marita; Lünsdorf, Heinrich; Häussler, Susanne; Santosa, Dwi A; Timmis, Kenneth N; Molinari, Gabriella Abstract: We report here the discovery, isolation, and chemical and preliminary biological characterization of a new antibiotic compound, 7-O-malonyl macrolactin A (MMA), produced by a Bacillus subtilis soil isolate. MMA is a bacteriostatic antibiotic that inhibits a number of multidrug-resistant gram-positive bacterial pathogens, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and a small-colony variant of Burkholderia cepacia. MMA-treated staphylococci and enterococci were pseudomulticellular and exhibited multiple asymmetric initiation points of septum formation, indicating that MMA may inhibit a cell division function. Mon, 01 May 2006 00:00:00 GMT http://hdl.handle.net/10033/12307 2006-05-01T00:00:00Z http://hdl.handle.net/10033/8763 Title: Cationic hydrous thorium dioxide colloids – a useful tool for staining negatively charged surface matrices of bacteria for use in energy-filtered transmission electron microscopy Authors: Lünsdorf, Heinrich; Kristen, Ingeborg; Barth, Elke Abstract: Background Synthesis of cationic hydrous thorium dioxide colloids (ca. 1.0 to 1.7 nm) has been originally described by Müller [22] and Groot [11] and these have been used by Groot to stain acidic glucosaminoglycans for ultrastructure research of different tissues by conventional transmission electron microscopy. Results Synthesis of colloidal thorium dioxide has been modified and its use as a suitable stain of acidic mucopolysaccharides and other anionic biopolymers from bacteria, either as whole mount preparations or as preembedment labels, is described. The differences in stain behavior relative to commonly used rutheniumred-lysine and Alcian Blue™ electron dense acidic stains has been investigated and its use is exemplified for Pseudomonas aeruginosa adjacent cell wall biopolymers. For the first time thorificated biopolymers, i.e. bacterial outer cell wall layers, have been analysed at the ultrastructural level with electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI), leading to excellent contrast and signal strength for these extracellular biopolymers. Conclusion Application of cationic hydrous ThO2 colloids for tracing acidic groups of the bacterial surface and/or EPS has been shown to be rather effective by transmission electron microscopy. Because of its high electron density and its good diffusibility it stains and outlines electro-negative charges within these biopolymers. In combination with ESI, based on integrated energy-filtered electron microscopy (EFTEM) Th-densities and thus negative charge densities can be discriminated from other elemental densities, especially in environmental samples, such as biofilms. Tue, 27 Jun 2006 00:00:00 GMT http://hdl.handle.net/10033/8763 2006-06-27T00:00:00Z http://hdl.handle.net/10033/8745 Title: Three Stages of a Biofilm Community Developing at the Liquid-Liquid Interface between Polychlorinated Biphenyls and Water Authors: Macedo, Alexandre José; Kuhlicke, Ute; Neu, Thomas R.; Timmis, Kenneth N.; Abraham, Wolf-Rainer Tue, 01 Nov 2005 00:00:00 GMT http://hdl.handle.net/10033/8745 2005-11-01T00:00:00Z